This invention relates to an anti-sway device for a carpet stretcher and to a carpet stretcher comprising such a device.
Carpet stretchers, examples of which are described in U.S. Pat. Nos. 3,692,278, 3,441,252 and 1,006,409, commonly comprise a tail block for bearing against a wall, a head that has teeth for gripping a carpet, a shaft or piston member fixed to the head, a cylinder member within which the shaft is slidable, a variable number (depending on the size of the carpet to be stretched) of telescopically interconnectable steel stretched tubes for connecting the cylinder member to the tail block, and a power unit for sliding the head relative to the cylinder member and longitudinally of the stretcher tubes. The power unit typically comprises a lever which is pivoted on the head and is attached to the cylinder member by a pivotable link so that the head is forced forwards when the lever is depressed and retracted when the lever is raised. The stretcher tubes thus serve to transmit compression forces in use.
A disadvantage of the known carpet stretchers is that the stretcher tubes are resiliently flexible and therefore tend to bow or sway sideways during stretching operations, as shown in FIG. 2A, reducing the efficiency of the stretching operation by reducing the compression force transmitted.
It has therefore been proposed to immobilize the stretcher tubes during stretching by bracing them against some heavy object or by fixing to the stretcher tubes a carpet gripper which has teeth or the like for gripping the carpet surface. The former proposal has the disadvantage that the heavy object must be moved each time the carpet stretcher is relocated sideways between stretching operations in order to stretch a different portion of the carpet. With the latter proposal, sideways relocation of the carpet stretcher between stretching operations and/or longitudinal movement of the stretcher tubes during stretching operations may lead to the carpet becoming damaged by the teeth of the carpet gripper.
In a conventional carpet stretcher, the stretcher tubes are telescopically interconnectable and comprise pairs of male and female tubes. the tubes are right circular cylindrical and each female tube has, spaced along the whole of its length, a number of pairs of diametrically opposed hles. The male tubes are of a size to slidingly engage in the female tubes and each is provided with just two pairs of diametrically opposed holes, one pair at each end of the tube. Inside each end of each male tube is a U-shaped spring having two outwardly extending buttons fixed thereto, one at each free end of the "U", for engaging in the pair of diametrically opposed holes of the male tube and a selected pair of holes of a female tube. Thus, the male tubes can be fixed at any desired position relative to the female tubes. In the carpet stretcher described above, the cylinder member comprises one of the female tubes, and the tail block has a single pair of opposed holes for engaging a mal tube. In this arrangement, the stretcher tubes cannot be rotated about their longitudinal axis.